Light water reactors (LWRs), including pressurized water reactors (PWRs) and boiling water reactors (BWRs), are thermal-neutron reactors than utilize water as both a coolant and a neutron moderator. An LWR generally includes a reactor core exhibiting fuel assemblies formed of and including fuel rods each comprising a cladding tube and fissile material structures (e.g., pellets, annular structures, particles, etc.) contained within the cladding tube. The fissile material structures typically comprise uranium dioxide (UO2) structures (e.g., UO2 pellets). The fuel rods are positioned relative to one another to provide neutron flux in the reactor core and produce thermal energy through controlled nuclear fission. Water is flowed through the reactor core to extract a portion of the produced thermal energy, which can then be utilized for the production of work.
Recently, triuranium disilicide (U3Si2) structures have been investigated as viable alternatives to the UO2 structures typically employed in LWR fuel rods. U3Si2 exhibits a number of favorable properties as compared to UO2. For example, there are approximately 17% more uranium atoms in a set volume of U3Si2 than there are in the same volume of UO2, given a constant percentage of theoretical density (e.g., 12.2 g/cm3 for U3Si2, and 10.96 g/cm3 for UO2) for both materials. Such high uranium loading has the potential to increase power ratings, extend fuel cycle length, and/or reduce enrichment requirements, all of which are economically beneficial. The higher uranium loading may also allow for the practical application of advanced cladding materials that carry a neutronic penalty compared to conventional cladding materials (e.g., Zircaloy materials). The higher thermal conductivity of U3Si2 as compared to UO2 can also reduce the anticipated centerline temperature in an U3Si2-fueled fuel rod as compared to an UO2-fueled fuel rod, which can have positive impacts on fuel rod performance in a variety of LWR accident conditions.
Accordingly, there is a continuing need for methods of forming U3Si2 structures suitable for use in LWRs, as well as for fuel rods including the U3Si2 structures and for fuel assemblies including the fuel rods. In addition, it would be desirable if such methods facilitated the formation of U3Si2 structures exhibiting relatively high densities, such as densities greater than or equal to about 11.47 g/cm3 (e.g., about 94.0 percent of the theoretical density of U3Si2).